Overrunning sprag type clutch



E. J. FARKAS OVERRUNNING SPRAG TYPE CLUTCH Nov. 27, 1951 v 2 SHEETS-SHEET 1 Filed Jan. 25, 1947 ATTORNEYS 1951 E. J. FARKAS 2,576,337

OVERRUNNING SPRAG TYPE CLUTCH) Filed Jan. 25, 1947 2 sHEET s-sHEET 2 E. J. FARKAS INVENTOR. J fe/xr A ATTORNEYS.

Patented Nov. 27, 1951 2,576,337 ovnmtnnnme s-PRAe TYPE CLUTCH Eugene J. Farkas. Detr Mich, asslgnor to For Motor Company, Dearborn, Mich a corporati n f Delawar plication January :25, 1 4.1, Serial No. 724347 1 Claim; (01. he ter) This. invention relates. enerally to cnc way clutches an more particularly to tiltalole gripn r type clu ches for connecting r latively rotat able races in one relative direction of rotation.

ne way or overrunning clutches of the tilt able gripper type are usually provided with a spring of the garter spring type threaded throu h holes in the in ividua grippers to form an ann his, the spring being arranged so as to tend to tilt the grippers in a direction to engage the races. It has. been found, however, that additional assistance must he provided to insure positive en gagement of the grippers with the races and to enable the grippers to rapidly respond to changes in relative rotation between the races. To ac: comp h this, inner and outer cages supporting the grippers are usually provided and. are ar rangedto frictionally engage the races to assist in controlling and actuating the grippers. Val

ious means have been proposed for providing this 1 f ictional en agement. For example, the ra s may initially be formed oval shaped so that they will frictionally a e the races when. assem bled therewith. Other methods include bend-v. ing th cross memb rs of. the case so as to iri tionally engage. the adjacent race, and buildin up certain portions of the cage with frictional ma erial such as silver solder- The disadvan:

, t gs of these constructions is that the additional iricti n. which is thus provided is present both clutch. incorporating a self=encrgialns iriction clement between the clutch cage and the adjacent. race. The friction element is initially formed of. different diameter than the diameter or the race with which it is to. he used so that when assembled the friction element will hav a light frictional engagement with the race. This friction is relatively small so that during the relat ve r t ion of the inner and outer races in a direction to disengage the one-way clutch there is little Power loss or Wear. In the other diree'e r tion. of relative rotation, the iriction element functions as a self-wra ping or self-energizing brake band. and the frictional retarding force isgrca ly increased The tiltab c erihpers are i lusr siii l controlled andresponq r m i y to changes relative. ro ation be w n the races The present invention thus provides sufileient frictional engagement to actuate the grippers rapidly and accurately in the power transmitting direction or relative rotation, reduces the possibllity of failure due to wear of the frictional element, and can readily be incorporated in one way clutches of the tiltable gripper type with only minor changes in the design of the latter.

Otherobjects and advantages of the present invention will be made more apparent as this description proceeds, particularly when considered in connection with the accompanying drawing, in which:

. Figure 1 is an and elevation, partly broken away and in section, of a one-way clutch cmbodying the present inven i n Figure 2 is a transverse cross sectional View taken. substantially on the plane indicated by the line 21-2 of F gure 1 Figure 3 is. a greatly enlarged fragmentary cross s c ional view through the inn r se and inner race, taken substantially on the plane indicated by the line .33 of Figure 1. I

' Referring now more P rticularly to t e awings the one-way clutch shown is adapted to connect an inner race H with an outer race l2. Al hough the races may be separate members, in many conventional installations of. one-way clutches as in automatic transmissions for auto motive use, the races are integrally .formed, in existing parts of the mechanism such as gears, hubs, etc. A series of ti tablc. grippers I?- are mounted between the coaxial inner nd outer v races, The sides of the grippers are flat and parallel and the. innerand outer ends are arcuatc surfaces curved about spaced, centers so that when the grippers are tilted counterclockwise as seen in Figure 1,, they will disengage the two races and. whcnthey' are tilted clockwi e wi l on gage the two races to transmitt pow therehe tween.

A entral openin 44 is provided in each rip per at an angle other than 90 to the sides of the. ripper to. receive an annular coil spring 16. The spring 16 is preferably of the garter spring type with its ends connected to form an annulus. The coil shrine l6, passing through h o liq e opening M in the grippers, tends. to tilt the grip cars in a clockwise direction to en age the races.

To hold the grippers in ansularly spaced no: sitions, inner and outercages I! and I8 are providaol The outer case 18 is a split annular rin nrovided with a series of openings it through which the radially outer ends. oi he sunscreen and more effective means for actuating the inner ends of the grippers.

The inner cage IT is formed in one piece 'and' constitutes axially spaced rims 2| and 22 joined by circumferentially spaced integral cross members 23. The radially inner ends of the grippers l3 extend through the resulting spaces formed between the cross members 23. It will be apparent that actuation of the inner cage IT in either direction will be effective to tilt the grippers in the corresponding direction by engagement of the inner ends of the grippers by cross members 23. a

The inner cage I! is freely rotatably mounted upon the inner race II, a clearance of a few thousandths being provided therebetween. Controlled frictional engagement between the inner race II and the inner cage IT is provided, however, by a pair of metallic friction bands 24 and 26. The bands are generally rectangular in cross section, with their maximum cross sectional dimension being in a radial direction. The inner surface of the band is preferably copper plated to reduce wear caused by frictional engagement between the bands and the inner race. The friction bands 24 and 26 are respectively mounted in circumferentially extending grooves 21 and 23, formed in the rims 2| and 22 of the inner'cage and opening radially inwardly. An anchor member 29, in the form of a pin having a rounded head and a square shank, is provided foreach friction band with the square shank mounted in a hole in the rim and the round end projecting into the groove formed in the rim. As best seen in Figure 1, the end 3| of each friction band is provided with a slot or notch 32 for engagement with the anchor pin 29. The remaining portion of each band is freely slidably mounted in its corresponding groove and terminates in a free end 33 spaced circumferentially'a slight distance from the anchored end 3| of the band.

' In its unstressed or free position before assembly, each frictionband is somewhat smaller in inside diameter than the outside diameter of the inner race I. It is therefore necessary to slightly expand the band to assemble the clutch upon the inne'r'race, the result being that the band is slightly distorted and is in light frictional contact with the inner race at all times. Having one end anchored and the oppositeend free, each band is of the self-wrapping or selfenergizing type. In other words, when the inner race rotates in a counterclockwise direction as indicated by the arrow in Figure 1, the friction of that portion of the-band between the anchored end 3| and the free end 33 helps to apply the band to\ the drum and to increase its retarding effect. Conversely, when the inner race rotates in the opposite or clockwise direction, the bands tend to unwrap and the frictional force is correspondingly much less. It has been found that in a construction of this type the frictional force in the wrapping direction may be as much as three or more times as great as the frictional force in the unwrapping direction. With these characteristics. the frictional bands admirably lend themselves to a precise and lasting control of the tiltable grippers.

In the counterclockwise or power transmitting direction of rotation of the inner race relative to the outer race, the self-wrapping effect of the friction band provides a sufficient frictional drag between the inner race II and the inner cage II to assi'st in tilting the "grippers in a clockwise direction to thus effectively and rapidly lock the inner and outer races together. In the clockwise or overrunning direction of rotation of the inner race relative to the outer race, the frictional drag between the friction band and the inner race is materially smaller, as pointed out above, and while sufficient to assist in tilting the grippers in a counterclockwise direction to release them is insufficient to cause material wear of the friction hand. The mechanism thus has an exceptionally long life and should operate for the life of a transmission without failure.

Axially extending grooves 34 are formed at spaced intervals in the frictional surface of the friction band 24 near its free or unanchored end 33. These grooves function to remove surface oil from the inner race H and increase the braking force therebetween.

Although one specific embodiment of the invention has been shown, it .will be understood that other arrangements are possible and are contemplated, within the spirit and scope of the appended claim. For example, if desired, a smaller or greater number of friction bands might be used and they might be anchored to the race rather than to the cage. elements could be used between the outer race and the outer cage, while in some instances it might be possible to eliminate the outer cage entirely. These, as well as other variations, are contemplated by the invention.

What is claimed is:

v A one way clutch for connecting inner and outer coaxial races comprising a plurality of tiltable grippers interposed between the races, radially spaced inner and outer cages each having a pair of axially spaced annular side rims integrally interconnected by a plurality of circumferentially spaced cross members holding the grippers in spaced relationship, the internal diameter of the siderims of said inner cage being slightly greater than the external diameter of said inner race to provide a slight clearance therebetween, each side rim of said inner cage having an annular groove formed therein with the grooves being rectangular in cross section and opening only into the radially inner surface of said rims to face said inner race, each of said grooves having a greater radial dimension than its axial dimension, an annular metallic band of rectangular cross section received within each of the grooves in said inner cage, each band having an axial dimension corresponding to the axial dimension of said grooves and slidably contained therein and a radial dimension slightly less than the radial dimension of said grooves to provide clearance in the bottom of said grooves when the bands are seated therein, each band consisting of a single convolution extending slightly less than 360 in circumference and in its free position having an internal diameter slightly smaller than the external diameter of said inner race so that when the cages and bands are assembled over the inner race the bands lightly engage the inner race throughout their entire circumferential extent, andanchoring means within each of saidgrooves anchoring one end of each of said bands to said In addition, similar frictional.

inner cage so that in one direction of rotation each single convolution band is expanded away from said inner race into the clearance space provided in the bottom of the groove and in the opposite direction of rotation is wound into tighter REFERENCES CITED The following references are of record in the file of this patent: 7

Number UNITED STATES PATENTS Name Date Locke July 9, 1901 Waite Mar. 2, 1910 Rundell Aug. 15, 1922 Brownlee May 2'7, 1934 Bethenod June 26, 1934 Collyear June 16, 1936 Dodge et a1. Jan. 9, 1945 Swenson Oct. 2, 1945 Dodge Nov. 27, 1945 Lund May 7, 1946 Nardone Apr. 11, 1950 

